Process for the production of iron carbonyl



United States Patent v V 2311x017 rRocEssFoR IPI-IEPRQDUGTION oF rRoN .cARBoNYL Leo Schlecht and I-Ielmut S'clileeht,Lullwigshafen (Rhine), and .Rudolf Staeger, Friedelsheim, Germany, iassignors -t0 Badische Anilin- & sodaeFabi-ik.Aktiengesellschaft, .Lntlwigshifen' (Rhine), Germany iNo Drawing. Application' February 6, 1952,

Serial No. 270,272

Claims priority, application Germany February 10, 1951 Claims. (Cl. 23-203) This invention relates to improvements in the production of an initial material for the manufacture of iron carbonyl.

In the industrial manufacture of iron carbonyl it is already known to use as initial material for the reaction with carbon monoxide a product containing iron and sulfur which has been obtained by a melting process. In order to obtain the melted product in a sufficiently divided form for the reaction, the melt has been converted into granulated form by allowing it to solidify in water or air. This method has the drawback, however, that the surface of the particles is oxidized during the granulation and a deterioration in the yield of carbonyl results because during the carbon monoxide treatment the oxide coating reacts only very slowly with the formation of carbonyl and moreover prevents access of the carbon monoxide to the iron present in the interior of the particles. A further drawback of granulation in water is that when the melt containing incandescent metallic iron meets water, hydrogen is evolved and often causes explosions of the such generated hydrogen-oxygen-mixtnre which are a, serious impediment to carrying out the granulation on a technical scale. These explosions occur the easier, the coarser the granules prepared. Small granules, on the other hand, have the drawback, that in the treatment with carbon monoxide under pressure they clog the high pressure furnace and, by the formation of dust, the circulating pump for the carbon monoxide.

We have now found that all the said drawbacks can be avoided and a fused product containing iron and sulfur which may be called iron matte and having a specially good reactivity as regards carbon monoxide, can be obtained by casting the fused product as a layer and allowing it to cool rapidly. It is advantageous to carry out the rapid cooling from the highest possible temperature, i. e. at the time when the melt is still in the liquid state in the casting bed. The rapid cooling is most simply effected by spraying with water; it-is possible by regulating the quantity of water to avoid gas explosions to a great extent.

In many cases a sufiiciently rapid cooling can be obtained with a current of air, especially when the thickness of the layer of the cast fused product is small.

The rapid cooling of the matte can also be effected by using material of good thermal conductivity for the molds, for example by using molds of cast iron or copper coated with graphite and which are preferably watercooled.

It is also possible to dispense with the use of a special cooling medium by so reducing the thickness of the layer of the cast fused product that so much heat is withdrawn by the casting bed from the underside of the melt and by the supernatant air that the cooling to room temperature takes place rapidly. This is usually attained with a layer thickness of not more than about 3 centimetres when using conventional cast iron plates as the lining material for the casting bed.

It is advantageous to select a sulfur content as low as possible because the thermal conductivity of iron matte 2,719,077 Ratented Sept. 27, 1955 92 .ponr in sulfur .is tgreater' and th'e co'oling ta kes place s-more rapidly than with'isulfurrich products. .Too low :a :sulfur "content, :however, is attended by the drawback tthatathe :castings are tough iand:therefore-.difliculty is :e'xsper ien'ced tin their Commi'nuti'on which --is 'necessary for :the "treatment with carbon monoxide. Generally spe'a'k- :ing a sulfur Icontent between 2 and 7'%, tpreferablyl'of about 4% ,fis therefore: chosen.

zForithe productionvdf -the.fusedlproduct containing sulfur and iron there may be'used'scrap :iron and Ipyrite's or iron sulfide residues which are not reacted during treatment with carbon monoxide to form iron carbonyl. Many other ferriferous materials may, however, also be fused with any sulfur-containing substances, as for example copper sulfide, provided that the molten liquid product obtained contains metallic iron dissolved in iron sulfide or another metal sulfide. For example iron oxide may be worked up with pyrites or iron ore, if desired with an addition of sodium sulfate and suitable slagformers, under reducing conditions to give a fused prodnot containing iron and sulfur.

The following example will further illustrate this invention but the invention is not restricted to this example.

Example An iron matte containing 93% of iron and 7% of sulfur smelted in a rotary furnace from scrap iron and the iron sulfide residues from the production of iron carbonyl, is cast in a bed lined with cast iron plates to give a plate which at the side of the outlet opening of the furnace is 4 centimetres thick and at the opposite side 7 centimetres thick. The thinner part of the layer, while in the molten liquid state, is rapidly cooled by spraying with a jet of water, whereas the thicker part of the layer cools slowly without special cooling measures.

The quenched part of the layer and the unquenched part of the layer are broken up separately into small pieces of a grain size of 5 to 10 millimetres. By separate treatment with carbon monoxide under a pressure of 200 atmospheres at a temperature of 200 to 220 C. and with the same speed of flow of carbon monoxide and in the same time, the whole of the iron contained in the quenched matte which is not combined as sulfide, is obtained as iron carbonyl, whereas from the unquenched matte only 45% of the said iron content is obtained as iron carbonyl.

What we claim is:

1. In a process for the production of iron carbonyl, the steps of casting a melt containing iron and a minor amount of sulfur in a layer of thickness not greater than about 4 centimeters, rapidly cooling the cast melt to about room temperature by spraying it with water, breaking the resulting casting into small particles, and reacting the particles thus formed with carbon monoxide.

2. In a process for the production of iron carbonyl, the steps of casting a melt containing iron and a minor amount of sulfur in a layer of thickness not greater than about 3 centimeters, quenching the cast melt to about room temperature, breaking the resulting casting into small particles, and reacting the particles thus formed with carbon monoxide.

3. In a process for the production of iron carbonyl, the steps of casting a melt containing iron and about 2 to 7% of sulfur in a layer of thickness not greater than about 3 centimeters, quenching the cast melt to about room temperature, breaking the resulting casting into small particles, and reacting the particles thus formed with carbon monoxide.

4. In a process for the production of iron carbonyl, the steps of casting a melt containing iron and about 2 to 7% of sulfur in a layer of thickness not greater than about 4 centimeters, rapidly cooling the cast melt to about room temperature by spraying it with water, breaking the resulting casting into small particles, and reacting the particles thus formed with carbon monoxide.

5. In a process for the production of iron carbonyl, the steps of casting a melt containing iron and about 2 to 7% of sulfur in a layer of thickness not greater than about 4 centimeters, rapidly cooling the cast melt to about room temperature by spraying it with water, breaking the resulting casting into small particles having a grain size on the order of 5 to 10 millimeters, and reacting the particles thus formed with carbon monoxide under a pressure on the order of 200 atmospheres and at a temperature on the order of 200 C. to 220 C.

References Cited in the file of this patent UNITED STATES PATENTS Schlect et a1. July 13, 1937 Glunz et a1. Apr. 16, 1940 Bartscherer July 8, 1941 SmaIIey Apr. 28, 1942 FOREIGN PATENTS Great Britain of 1868 Great Britain Dec. 18, 1929 Great Britain Jan. 27, 1930 Great Britain Nov. 22, 1935 

1. IN A PROCESS FOR THE PRODUCTION OF IRON CARBONYL THE STEPS OF CASTING A METAL CONTAINING IRON AND A MINOR AMOUNT OF SULFUR IN A LAYER OF THICKNESS NOT GREATER THAN ABOUT 4 CENTIMETERS, RAPIDLY COOLING THE CAST MELT TO ABOUT ROOM TEMPERATURE BY SPRAYING IT WITH WATER, BREAKING THE RESULRING CASTING INTO SMALL PARTICLES, AND REACTING THE PARTICLES THUS FORMED WITH CARBON MONOXIDE. 